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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Effect of localized structural perturbations on dendrimer structure

Gabriel, Christopher J. 14 September 2006 (has links)
No description available.
2

Self-Assemblies Driven by the Hydrophobic Effect

Gan, Haiying 17 December 2011 (has links)
Water is a simple molecule but is an essential part of life. One key aspect of the properties of water is the hydrophobic effect, and whilst there is an appreciation of this phenomenon at the macro-scale (raindrops falling off leaves) and the micro-scale (the structure of cellular systems), a complete understanding at the molecular level still eludes science. Addressing this issue, our studies involve synthetic supramolecular compounds that assemble in water via the hydrophobic effect. First of all, a novel water-soluble deep-cavity cavitand was synthesized. It possesses four endo methyl groups on top rim of the cavitand, eight water-solubilizing carboxylic acid groups coated on the cavitand exterior, and a relatively large hydrophobic interior. Compared to a previous well-studied water-soluble deep-cavity cavitand octa-acid (OA), this novel cavitand (TEMOA) possesses a non-monotonic assembly profile in the presence of a homologous series of straight-chain alkanes. Three supramolecular species were observed: 1:1, 2:2, and 2:2 and they are approximately isoenergetic. Second, we examined the guest-controlled self-sorting in assemblies. A mixture of OA and TEMOA formed hetero-capsular complex driven by the hydrophobic effect. The extent of homo- or hetero-dimerization is intimately tied to the size of the guest being encapsulated. TEMOA is less predisposed to dimerize than OA, thus TEMOA possesses the ability to form various self-assembled states, such as tetrameric and hexameric assemblies. Furthermore, we also discussed our observation of how external stimuli such as changing the nature or concentration of a co-solute salt influences a unique, unusual transition from one assembled state to another.
3

pH Dependence of Acrylate-Derivative Polyelectrolyte Properties

Swift, Thomas 07 May 2018 (has links)
yes / There are many polymers formed of acrylate monomers in existence. Here we interrogate four commonly-used examples and study how their solution properties are pH dependent, or how their state of ionisation can affect their solution properties. Poly(acrylic acid) and poly(methacrylic acid) are both polyelectrolytes, with ionisable functional groups that make them stimuli responsive, changing their hydrodynamic volume. Poly(acrylamide) is a mass-produced material used in a variety of industrial applications, often with an anionic and cationic co-monomer, which dictates both its efficacy and impact on the environment. Poly(N-isopropyl acrylamide) is a thermally responsive material with applications in smart bioengineering. In solution, these materials can interact with each other due to competing hydrogen bonding interactions. However, this interpolymer complexation is dependent on both the ionisation, and the conformational state, of the polymers involved. This review focuses on the results from fluorescence tagging and turbidimetric techniques.

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